Multiprotocol label switching (MPLS) is a scheme in high-performance telecommunication networks which directs and carries data from one node to the next node. The multiprotocol label switching mechanism assigns labels to data packets. Packet forwarding decisions from one node to the next node are made solely on the contents of the label for each data packet, without the need to examine the data packet itself.
Generalized Multiprotocol Label Switching (GMPLS) is a type of protocol which extends multiprotocol label switching to encompass network schemes based upon time-division multiplexing (e.g. SONET/SDH, PDH, G.709), wavelength multiplexing, and spatial multiplexing (e.g. incoming port or fiber to outgoing port or fiber). Multiplexing, such as time-division multiplexing is when 2 or more signals or bit streams are transferred simultaneously. In particular, time-division multiplexing (TDM) is a type of digital multiplexing in which 2 or more signals or bit streams are transferred simultaneously as sub-channels in one communication channel, but are physically taking turns on the communication channel. The time domain is divided into several recurrent time slots (TS) of fixed length, one for each sub-channel. After the last sub-channel, the cycle starts all over again. Time-division multiplexing is commonly used for circuit mode communication with a fixed number of channels and constant bandwidth per channel. Time-division multiplexing differs from statistical multiplexing, such as packet switching, in that the time slots are returned in a fixed order and pre-allocated to the channels, rather than scheduled on a packet by packet basis.
Generalized Multiprotocol Label Switching includes protection and recovery mechanisms which specifies predefined (1) working connections within a shared mesh network having multiple nodes and communication links for transmitting data between the nodes; and (2) protecting connections specifying a different group of nodes and/or communication links for transmitting data in the event that one or more of the working connections fail. In other words, when a working connection fails, the Generalized Multiprotocol Label Switching protocol automatically activates one of the protecting connections into a working connection for redirecting data within the shared mesh network.
However, the protection and recovery mechanisms defined in GMPLS have overlooked a number of issues when scaling to large optical shared mesh networks. Shared mesh protection (SMP) is a common protection and recovery mechanism in transport network, where multiple protect circuits can share the same set of time slots for protection purposes. In SMP, one work circuit is protected by one or many protect circuits. And these protect circuits from different work can share the time slots on network links. Depending on network planning requirements, user may identify the set of network links which can be used to provisioned protect circuit.
In shared mesh protection, each protecting connection is likely established over a set of time slots that are shared by multiple other connections. Upon the detection of working connection failure, the head end nodes may trigger the activation of the protecting connections, and redirect user traffic immediately after. The time slot assignment in a link is still a part of the control-plane Connection Admission Control (CAC) operation taking place on each shared protection node. The time slot assignment and sharing method among different protect circuits on the shared links is one of most important aspect of SMP. Thus, there is a constant pressure to maximize the sharing in the network by optimally utilizing the time slots.
This creates complexities and challenges in time slot sharing on a network link among multiple protect circuits from different work circuit. For example, the protect circuit in the network can be created in any order and each protect circuit may be protecting a set of network failures, or Shared Risk Link Group (SRLG) in the network, from the work circuit path. A number of provisioned protect circuit in a link creates a foot print of protected SRLGs. For a new protect path time slot allocation request, there may be a number of options available in terms of time slot on the link to choose from the current foot print by sharing with them. This problem becomes severe when the network link is bundled, i.e., consists of a number of component links. In a bundled link, the allocation has to be such that it avoids the spray of protection circuits among the component links, i.e., select the TS in a way to avoid fragmentation of Bandwidth (BW) among components. In addition, a service provider/network operator may want to define different protection criterion and sharing requirements for different services. This brings the need of having different class of services (COS) of different protect circuits, e.g., high priority (HP) and Low priority (LP). The system must be able to provide such service differentiation.
Accordingly, there is a need for systems, apparatus, and methods that improve upon conventional approaches including the improved methods, system and apparatus provided hereby.